Ceroid lipofuscinosis or Batten disease is an inherited progressively degenerative disorder with fatal outcome in a few years after the manifestation of clinical symptoms. Recent identification of 60-70 percent of lysosomal storage material as ATP synthase c-subunit in the brain of an ovine model of this disease and also in the late infantile and juvenile forms of Batten disease has, for the first time, provided an excellent understanding of the biochemical defect in this disorder. Although no structural abnormality in synthase c-subunit has been found, the possibility of a defect in post-translational modification of this subunit can not be ruled out. The proposed studies are aimed at understanding whether the defect in late infantile and juvenile forms as well as in the ovine model of ceroid lipofuscinosis is in the ATP synthase c subunit or in the lysosomal hydrolase which normally degrades it.